#region License
/*
 * PayloadData.cs
 *
 * The MIT License
 *
 * Copyright (c) 2012-2019 sta.blockhead
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
#endregion

using System;
using System.Collections;
using System.Collections.Generic;

namespace WebSocketSharp
{
  internal class PayloadData : IEnumerable<byte>
  {
    #region Private Fields

    private byte[] _data;
    private long   _extDataLength;
    private long   _length;

    #endregion

    #region Public Fields

    /// <summary>
    /// Represents the empty payload data.
    /// </summary>
    public static readonly PayloadData Empty;

    /// <summary>
    /// Represents the allowable max length of payload data.
    /// </summary>
    /// <remarks>
    ///   <para>
    ///   A <see cref="WebSocketException"/> will occur when the length of
    ///   incoming payload data is greater than the value of this field.
    ///   </para>
    ///   <para>
    ///   If you would like to change the value of this field, it must be
    ///   a number between <see cref="WebSocket.FragmentLength"/> and
    ///   <see cref="Int64.MaxValue"/> inclusive.
    ///   </para>
    /// </remarks>
    public static readonly ulong MaxLength;

    #endregion

    #region Static Constructor

    static PayloadData ()
    {
      Empty = new PayloadData (WebSocket.EmptyBytes, 0);
      MaxLength = Int64.MaxValue;
    }

    #endregion

    #region Internal Constructors

    internal PayloadData (byte[] data)
      : this (data, data.LongLength)
    {
    }

    internal PayloadData (byte[] data, long length)
    {
      _data = data;
      _length = length;
    }

    internal PayloadData (ushort code, string reason)
    {
      _data = code.Append (reason);
      _length = _data.LongLength;
    }

    #endregion

    #region Internal Properties

    internal ushort Code {
      get {
        return _length >= 2
               ? _data.SubArray (0, 2).ToUInt16 (ByteOrder.Big)
               : (ushort) 1005;
      }
    }

    internal long ExtensionDataLength {
      get {
        return _extDataLength;
      }

      set {
        _extDataLength = value;
      }
    }

    internal bool HasReservedCode {
      get {
        return _length >= 2 && Code.IsReserved ();
      }
    }

    internal string Reason {
      get {
        if (_length <= 2)
          return String.Empty;

        var raw = _data.SubArray (2, _length - 2);

        string reason;
        return raw.TryGetUTF8DecodedString (out reason)
               ? reason
               : String.Empty;
      }
    }

    #endregion

    #region Public Properties

    public byte[] ApplicationData {
      get {
        return _extDataLength > 0
               ? _data.SubArray (_extDataLength, _length - _extDataLength)
               : _data;
      }
    }

    public byte[] ExtensionData {
      get {
        return _extDataLength > 0
               ? _data.SubArray (0, _extDataLength)
               : WebSocket.EmptyBytes;
      }
    }

    public ulong Length {
      get {
        return (ulong) _length;
      }
    }

    #endregion

    #region Internal Methods

    internal void Mask (byte[] key)
    {
      for (long i = 0; i < _length; i++)
        _data[i] = (byte) (_data[i] ^ key[i % 4]);
    }

    #endregion

    #region Public Methods

    public IEnumerator<byte> GetEnumerator ()
    {
      foreach (var b in _data)
        yield return b;
    }

    public byte[] ToArray ()
    {
      return _data;
    }

    public override string ToString ()
    {
      return BitConverter.ToString (_data);
    }

    #endregion

    #region Explicit Interface Implementations

    IEnumerator IEnumerable.GetEnumerator ()
    {
      return GetEnumerator ();
    }

    #endregion
  }
}